Quenching long range magnetic excitations in oxygen sub-lattice reconstructed thin films of (SrCuO₂)_n/(SrTiO₂)₂ superlattices

Multi-layered thin cuprate films allow inducing subtle structural changes with which local crystal field and long range magnetic excitations can be finely tuned. In (SrCuO₂)_n/(SrTiO₂)₂ cuprate superlattices, in particular, a structural transformation from a bulk infinite planar to a sheet-like local domain environment has recently been predicted and subsequently observed. Here we present results on the influence of this subtle structural reconstruction on the collective magnetic excitations using high-resolution resonant inelastic x-ray scattering (RIXS) at the Cu L₃ edge. While bulk like infinite layer films exhibit magnon excitations throughout the whole Brillouin zone, decreasing the thickness of the cuprate layers leads to quenching of the magnons starting from the Gamma point successively to the zone boundary, allowing us to study the coherence length of the collective long range magnetic excitations in these cuprate superlattices.